Browsing by Author "Arya A."

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Dielectric relaxation and AC conductivity of TiO2 nanofiller dispersed polymer nanocomposite
(American Institute of Physics Inc., 2019) Arya A.; Sadiq M.; Sharma A.L.
The Lithium-ion conducting polymer nanocomposite (PNC) has been synthesized by the standard solution cast technique in the skeleton of PEO-PVC blend with a different content of Titanium oxide (TiO2) as nanofiller. The lithium hexafluorophosphate (LiPF6) was used as the salt. The dielectric strength decreases with frequency and is attributed to the dominance of the electrode polarization effect. The highest dielectric strength and lowest relaxation time (1.88 ns) were achieved for the 15 wt. % TiO2 (PPS15T) PNCs when compared to other concentrations. The PPS15T exhibits the highest dc conductivity 2.34×10−5 S cm−1 at RT. The dielectric strength (Δε) and relaxation time (τε′) were in good agreement with the dc conductivity (σdc). An interaction scheme has also been proposed to highlight the interactions between the polymer, salt and nanofiller in most visual manner.
Dielectric relaxations and transport properties parameter analysis of novel blended solid polymer electrolyte for sodium-ion rechargeable batteries
(Springer New York LLC, 2019) Pritam; Arya A.; Sharma A.L.
A novel blended solid polymer electrolyte comprising polyethylene oxide and polyvinylpyrrolidone polymers for blending and sodium nitrate (NaNO3) as ion conducting species has been optimized via standard solution-cast technique. XRD, FESEM, and FTIR were performed to obtain the information about the structural changes, morphology, and microstructural changes (polymer–ion and ion–ion interactions) of the solid polymer electrolyte films. The electrochemical impedance spectroscopy, linear sweep voltammetry, and i–t characteristics were performed to evaluate the ionic conductivity, voltage stability window, and ion transference number. The impedance study was done in a broad temperature range (40–100 °C). The DSC and TGA were used to obtain information about the thermal transitions and thermal stability of prepared films. The ion dynamics is further investigated by analyzing the complex permittivity, loss tangent, and complex conductivity. All the plots were fitted through established theoretical model/expressions in whole frequency window to obtain dielectric strength, ion conduction path behavior, and relaxation time. Transport parameters such as number density (n), mobility (μ), and diffusion coefficient (D) of mobile ions were obtained by three methods and compared satisfactorily. Lastly, a coherent mechanism for the migration of charge transport carriers within the solid polymer composites has been proposed based on the performed experimental outcome.
Impact of shape (nanofiller vs. nanorod) of TiO2 nanoparticle on free-standing solid polymeric separator for energy storage/conversion devices
(John Wiley and Sons Inc., 2019) Arya A.; Saykar N.G.; Sharma A.L.
We report the investigation on examining the impact of nanofiller (NF)- versus nanorod (NR)-shaped titanium oxide (TiO2) nanoparticle on the structural, electrochemical, transport, thermal, and dielectric properties of the solid polymer electrolyte (SPE). Thin SPE films comprising of poly(ethylene oxide), sodium hexafluorophosphate, and dispersed with TiO2 NF, TiO2 NR (synthesized by hydrothermal route) has been prepared via solution cast technique. The shape of nanoparticle influences the morphological and structural properties as observed in field emission scanning electron microscope and X-ray diffraction analysis. The highest ionic conductivity was exhibited by the NR dispersed system and is higher than NF dispersed system for all recorded concentration consistently. It is attributed to the formation of the long-range conductive path with NR when compared with NF. In addition, the electrochemical stability window is much higher (~5 V) than the NF-doped system. Furthermore, the dielectric properties of SPE were investigated and fitted in the complete frequency window (1 Hz–1 MHz; T = 40–100 °C @ 10 °C). It is observed that the NR dispersed system shows higher dielectric strength and low relaxation time with respect to NF dispersed system. The results suggest that the NR dispersed SPE possess enhanced properties and is more appropriate for an application in high energy density solid‐state Na ion batteries. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 47361.
Selection of best composition of Na+ ion conducting PEO-PEI blend solid polymer electrolyte based on structural, electrical, and dielectric spectroscopic analysis
(Institute for Ionics, 2019) Pritam; Arya A.; Sharma A.L.
In this paper, we report the investigation on structural, electrical, dielectric properties, and ion dynamics of novel blend polymer electrolyte matrix (PEO-PEI) complexed with sodium hexafluorophosphate salt. All the solid polymer electrolyte films have been synthesized via solution cast method. The SPE films were characterized by the X-ray diffraction, field emission scanning electron microscope, impedance-dielectric spectroscopy, and thermogravimetric analysis. The morphology of the SPE alters with salt addition and confirms the blend polymer complex formation. The FTIR analysis evidenced the complex formation, and increase in the fraction of free ions is achieved. The ionic conductivity exhibits a maximum at the stoichiometric ratio O/Na = 10 and follows the Arrhenius behavior. The fraction of free ions is maximum for the SPE film with the highest ionic conductivity. The optimum electrolyte possesses a voltage stability window of about 4 V, excellent thermal stability up to 380 °C, and high ionic transference number (~ 1). The complex permittivity and conductivity have been simulated in whole frequency window to extract relaxation time and dielectric strength. The dielectric constant and relaxation time exhibited sequentially a maximum and minimum for the SPE film with the highest ionic conductivity. The loss tangent peak shifts toward high frequency with addition of salt, and it infers the faster ion dynamics in the polymer matrix. Then the ion transport parameters number density of charge carriers (n), ion mobility (?), and diffusion coefficient (D) have been obtained by three methods (FTIR, impedance spectroscopy, and loss tangent method) and are in absolute correlation with the impedance results. An ion transport mechanism has been proposed based on experimental findings.
Structural, electrical and ion transport properties of free-standing blended solid polymeric thin films
(Springer Verlag, 2019) Arya A.; Sadiq M.; Sharma A.L.
Blended solid polymeric thin films based on PEO–PVP complexed with LiBOB were synthesized by solution cast technique. The effect of salt on morphology, structure and electrochemical properties was examined. The XRD and FESEM analyses reveal the enhancement of amorphous content on salt addition. The FTIR spectroscopy evidences the complex formation and presence of various microscopic interactions. The ionic conductivity for the optimized system has been estimated and found to be two orders higher than the salt-free system, i.e., ~ 5.1 × 10−6 S cm−1 (@40 °C), and remains increasing with temperature i.e. 6.5 × 10−4 S cm−1 (@100 °C) for O/Li = 16. The enhancement of ionic conductivity is attributed to increase in the number density of mobile ions as concluded by the Rice and Roth model. The high tion (~ 0.99) evidences the ionic nature of complexed electrolyte. DSC analysis evidences the suppression of crystallinity and shift of glass transition and melting temperature toward lower temperature implies the enhancement of the amorphous content and forms the rubbery nature of the thin films which support the faster ion conductions. Finally, an interaction scheme is proposed for a better explanation of the ion transport on the basis of experimental findings.